During the microelectronic device fabrication process, multiple integrated circuits are formed upon the surface of substrate. Examples of substrates include, but are not limited to silicon wafers, gallium arsenide wafers and the like. Each integrated circuit consists of micro electronic devices electrically interconnected with conductive traces known as interconnects. Interconnects are patterned from conductive layers formed on the surface of the substrate. The ability to form stacked layers of interconnects has allowed for more complex micro circuits to be implemented in and on relatively small surface areas of the substrate. With the number of micro circuits increasing and becoming more complex, the number of layers of a substrate are increasing. Accordingly, planarity of the substrate surface becomes a critical dimension, and is now found to be important to maximizing circuit performance.
Chemical mechanical polishing (CMP) is a known method of planarizing the surface of a layer of a substrate. CMP combines chemical etching and mechanical abrasion to remove roughness on the surface of the substrate. FIG. 1 is an example of a top view of a known CMP process. During the CMP process, the substrate 10, being attached to a head 12, is inverted such that the integrated circuit-embodied surface opposably faces a polishing pad 14. Polishing pad 14 is saturated with a slurry containing abrasive particles and a mild chemical etchant that softens or catalyzes the exposed surface being planarized. The polishing pad 14 is fixedly attached to a turntable or platen (not shown). The substrate 10 is polished by placing the substrate 10 into contact with the polishing pad 14 while the polishing pad 14 is rotated on the platen. The surface roughness of the integrated circuit-embedded embedded surface of the substrate 10 is removed by the combined action of chemical softening of the exposed surface material and physical abrasion brought about by relative movement between the polishing pad 14, the slurry and the substrate 10.
As portions of the substrate 10 are removed by the polishing pad 14, a combination of slurry and debris tends to clog the surface of the polishing pad 14, such that over time, the polishing pad 14 becomes less effective. The surface of polishing pad 14 is cleaned by conditioning disc 16, which has an abrasive surface that engages the polishing pad surface. Known conditioning discs are typically made of stainless steel and have an abrasive surface, such as coatings like diamond grit or with surface marks. The abrasive surface of conditioning disc 16, however, tends to clog with slurry and debris, thereby rendering less and less effective over time. The spent conditioning discs are removed from the CMP machine and either treated to refresh the conditioning surface or discarded. This process is time consuming, expensive and complicates achieving accurate planarity due to uneven declining effectiveness over the life of the conditioning disc.
Accordingly, new configurations and methods are needed for providing a conditioning disc that will resist clogging, and which provides for minimal downtime and replacement, thereby reducing manufacturing costs.